Harry Kim, civil defense administrator for the southeasternmost island of Hawaii, said a hurricane watch could be issued soon for the main city of Hilo and the southeast coastal areas.

''I feel there is a possibility the island of Hawaii, especially the coastal areas of Puna and Ka'u, will suffer effects due to damaging surf at the very least,'' Kim said.

A high surf advisory was already in effect for the eastern shores.

Officials in Honolulu on the island of Oahu, 200 miles away, said they would be prepared for heavy rain as early as Friday if Ignacio did not radically change course.

The hurricane was moving with increased speed but its winds had slowed somewhat, weather forecasters said.

Air Force hurricane hunter reconnaissance planes found Ignacio's center 565 miles east-southeast of Hilo at 8 a.m. Wednesday. Its strongest sustained winds had decreased from 130 mph to 105 mph since the 2 a.m. check. Gusts to 125 mph were measured, a decrease from the previous 160 mph.

The National Weather Service said Ignacio was maintaining a speed of 12 mph, an increase since Tuesday, but its west-northwest trajectory seemed to be shifting to a more westerly track.

''It looks like it's beginning to move a little farther to the south, and the winds have decreased by 25 mph, so those are two significant changes. However, Hurricane Ignacio is still a potent hurricane,'' said meteorologist Clarence Lee.

Ignacio was forecast to be about 345 miles east-southeast of Hilo by 2 a.m. today.